1. Field of the Invention
The present invention relates to a copying apparatus which forms an image by use of electrophotographic technology.
2. Description of the Related Art
In recent years, electrophotographic copying apparatuses have come into use not only in offices and factories but also in ordinary homes. Under the circumstances, there is a demand for development of a copying apparatus which is compact in size, reliable in operation, and easy to handle.
Recently, a compact-in-size copying apparatus can be obtained by utilizing the light source of an exposure unit for electrically discharging a photosensitive drum. In this copying apparatus, a halogen lamp is employed in place of a fluorescent lamp, so as to stabilize the light source and shorten the actuation time.
However, a halogen lamp emits a far larger amount of heat than a fluorescent lamp. Therefore, the lamp may thermally damage a reflector for directing the lamp light in a predetermined direction.
In general, a charging unit must be accurately positioned with reference to a photosensitive drum, for reliably charging the photosensitive drum. A conventional copying apparatus comprises a charger frame supporting the charging unit and a support frame supporting the photosensitive drum, and the changer frame is not attached to the support frame but to another apparatus frame. With this construction, it is difficult to provide accurate positioning between the charging unit and the photosensitive drum.
In a copying apparatus capable of producing color copies, a plurality of developer cartridges containing different-color developers are prepared, and these cartridges are selectively loaded in the copying apparatus. To let the operator know the color of the developer to be used, a conventional copying apparatus comprises an electric circuit for detecting the type of developer cartridge loaded in the apparatus, and an indicator provided on the control panel of the apparatus to indicate results of the cartridge detection. Due to this construction, the conventional color copying apparatus includes a large number of parts or components, and is therefore complex and large in size.
Not only a developer cartridge used in a color copying apparatus but also a developer cartridge used in an ordinary monochromatic copying apparatus has a rotating shaft for agitating the developer, and a gear attached thereto. When the cartridge is loaded in a copying apparatus, the gear of the rotating shaft engagemens a driving gear provided in the copying apparatus. However, the gear of the rotating shaft and the driving gear of the copying apparatus do not always smoothly engage with each other. In some cases, the teeth of the two gears collide with each other, resulting in damage to the teeth. Therefore, the conventional copying apparatus is not very reliable in operation.
As mentioned above, the conventional copying apparatuses employ a large number of parts or components, so that it still has much room for miniaturization. In addition, the conventional apparatus is not satisfactorily reliable in operation.